Fluid skimmers have been used for many years for separating one or more immiscible fluids in a fluid composition. One common application of skimmers is for removing oil from contaminated water.
Most skimmers used in the past employ floating type collectors which float on the surface of the liquid being skimmed and which are coupled to an outlet with a flexible hose. An example of this type of skimmer is shown in U.S. Pat. No. 3,616,923 invented by Ernest K. Haley. This type of skimmer includes a floating chamber having a collection slot which is partially submerged and partially exposed. This skimmer has several disadvantages. Because the collection slot is partially exposed, debris can enter the slot thus clogging the skimmer and reducing the efficiency of the skimmer or blocking it completely. In addition, as the level of the fluid in 2 storage tanks or separation vessels falls, the flexible hose may rise to the surface of the fluid if insufficient fluid is available to fill the hose. In this case, the flexible hose fills with air and a vapor lock may develop. If a vapor lock develops, the skimmer may not restart when needed.
Another floating type skimmer is shown in U.S. Pat. No. 1,107,391, invented by Welch. This skimmer is also coupled to a flexible hose and is also prone to the vapor lock problem described above. In addition to this problem, this skimmer uses a annular screen surrounding the intake of the skimmer to prevent the entry of debris. However, if any significant wave action is present, or if the skimmer is used in an open environment, debris may be washed over the screen or fall in the uncovered top of the device thus clogging it. In addition, the buoyancy of this skimmer changes as it fills with oil or when oil is removed. Therefore, it is impossible to control the depth of the skim with any accuracy.
In addition to the problems noted above, skimmers which employ flexible hoses drift in an uncontrolled manner in the fluid being skimmed. It is therefore difficult to control the exact position of the skimmer making it impossible to skim to very precise depths. In addition, in situations where water accumulates in the flexible hose, oil will be unable to dislodge the water thus blocking skimmer operation.
Another type of skimmer is shown in U.S. Pat. No. 3,702,134, invented by Henning. With this type of skimmer, rigid tubing supports the skimmer apparatus. However, the flat surface of the skimmer is prone to collecting debris thus changing the buoyancy of the skimmer and affecting the accuracy of the skim depth. In addition, the drain lines of this apparatus must be constantly filled with fluid to maintain equilibrium in the complicated counterbalance system used in this device.
From the foregoing, no skimming apparatus is known which is highly resistant to debris, which is self-adjusting and self-leveling and which provides a highly accurate and controllable skim depth in a wide variety of conditions.